Cooling system for internal combustion engines



c. R. BUTLER 2,799,260 1 TERNAL COMBUSTION ENGINES Filed Oct. 15, 1.955

July 16, 1957 COOLING SYSTEM FOR IN R, R 2 m:

HTT'OP/VEYS.

United States Patent COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINES This invention relates to a cooling system for internal combustion engines and more particularly to that type of cooling system in which means are provided for maintaining the system at a pressure above atmospheric. Such systems commonly embody a pressure-relief valve which prevents the escape of any air, vapor, or liquid from the system until the pressure therein attains a predetermined value. Commonly, the pressure-relief valve is associated with the radiator filler cap and located at the highest point in the system. a

When the engine is not operating and the coolant cold, prior systems of the type described contain a pocket of air at the top of the radiator unless, of course, the system has just been filled. Accordingly, when the engine is placed in operation and the temperature of the coolant begins to rise, the air pocket can contract and accommodate a substantial thermal expansion of the liquid coolant before attaining a pressure suflicient to cause opening of the relief valve. If the quantity of gaseous material in the system is sufiicient, it is possible that the desired operating pressure -i. e., a pressure just below that necessary to open the relief valve-will never be attained.

It is an object of this invention to produce an engine cooling system of the pressure type in which the desired Operating pressure will be attained more quickly, will be maintained more effectively during engine operation, and will persist for a greater length of time after operation of the engine has ceased. Another object of the invention is to reduce the likelihood of pockets of gaseous material within the cooling system.

In carrying out my invention, 1 associate with the cooling system an auxiliary reservoir which is preferably open to the atmosphere and connected to the cooling system to receive coolant escaping past the pressure-relief valve. The lower portion of such auxiliary reservoir is connected to the inlet of the coolant-circulating pump through a check valve opening toward the pump to prevent return to the reservoir of any liquid once withdrawn therefrom by the pump.

In the accompanying drawing, which illustrates an embodiment of the invention:

Fig. l is an elevational view, somewhat diagrammatic in character, illustrating a portion of an engine and associated cooling system; and

Fig. 2 is a fragmental vertical section on an enlarged scale illustrating structural details of the cooling system.

In Fig. 1 I have shown, by way of illustration, a portion of a coolant-jacketed automobile engine 10, a radiator 11, and an engine-driven pump 12 for circulating coolant through the radiator and the jacket of the engine. The inlet 13 of the pump 12 is connected to the lower portion of the radiator 11 through a conduit 14, while the Outlet 15 of the coolant jacket is connected to the upper portion of the radiator through a conduit 16. At its upper end, the radiator 11 is provided with a filler neck 17 and a removable closure 18 therefor.

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As shown in Fig. 2, the closure 18 has associated with it a valve mechanism designated in its entirety by the reference numeral 21 and including an outwardly opening valve 22 urged against a seat 23 by a compression spring 24. The cooling system is sealed by the valve 22, which remains seated until the pressure Within the system builds up to a predetermined point dependent upon the strength of the spring 24. If that pressure is exceeded, the spring 24 yields and the valve 22 opens to permit escape of fluid through an outlet opening 26 provided in the side of the neck 17 outwardly beyond the valve-seat 23. To prevent a vacuum of too great a value from occurring within the cooling system as a result of a drop in temperature following termination of engine operation, the valve device 21 commonly includes an inwardly opening valve 27 urged outwardly against a valve-seat 28 by a compression spring 29. The opening through the valve seat 28 communicates with the atmosphere, as through the opening 26, so that the valve 27 can open to admit atmospheric air to the cooling system and limit the extent of the vacuum created therein when the temperature of the system drops.

As so far described, the cooling system is of a common type. In practice, the outlet opening 26 communicates with an overflow tube Or pipe which extends downwardly to a point near the bottom of the radiator so that liquid expelled from the cooling system past the valve 22 will not escape into the engine compartment.

:past the valve 27 when the temperature of the system drops following termination of engine operation.

To incorporate my invention in a system of the typedescribed, I provide an auxiliary tank or reservoir 31 which is conveniently located near the top of the radiator 11.

i The upper portion of such reservoir communicates with the outlet opening 26 in the tiller neck 17 as through a conduit 32 and, if desired, may also be provided with a filler cap 33. The lower portion of the reservoir 31 is connected to the inlet 13 of the pump 12 through a conduit 35 in which there is incorporated a check valve 36 opening toward the pump. To accommodate a possible excess of liquid, the auxiliary tank 31 may be provided with an overflow tube or pipe 37 communicating with the reservoir near the top thereof. The tube 37 serves to vent the upperportion of the tank 31 to atmosphere, but additional venting may be provided if desired.

the connection between the reservoirtlil and the conduit' 35 may be controlled by a float valve designed to close should the reservoir 31 become empty. As shown, such float valve comprises a buoyant sphere adapted upon a drop of liquid level in the reservoir to engage a valve-seat 41 surrounding the outlet into the conduit 35. The valve 40 is held in operative association with the seat 41 as by an appropriate cage 42.

The system illustrated and above described, operates in the following manner: Let it be assumed that the engine 10 is not operating, that the sealed cooling system is substantially 'at atmospheric pressure and temperature, and that a pocket of air exists at the top of the radiator below the valve 22. When the engine is placed in operation, the pump 12 will reduce the pressure at the inlet 13 and will thereby cause liquid to be drawn from the aux iliary tank 31 past the check valve 36 and into the cooling system proper. By increasing the volume of liquid in the cooling system and thereby reducing the volume of the air pocket, the introduction of liquid from the tank 31 will increase pressure at all points in the system; and liquid will continue to be introduced until the pressure will be inducted from the tank 31. As the engine warms Any material. so expelled from the system as a result of a temperature rise therein is lost and is later replaced by air admitted.

up, the coolant will expand and the pressure within the system Will rise further. If the pressure rises sufiiciently to open the valve 22, some of the air will escape; but if it does not rise to that value, the liquid initially introduced from the tank 31 will still remain in the system, since val during which the temperature of the coolant has dropped, more liquid will be introduced from the tank 31; so that even if all the air Was not expelled during the first period of engine operation, the continued addition consequential because of the rapid pressure rise which results in the absence of an air pocket. Any liquid which escapes past the valve 22 once all air is expelled from the system will return to the auxiliary tank through the conduit 32.

It may be noted that in a cooling system incorporating into the system from the auxiliary tank 31 past the check valve 36.

The function of the float valve 40 is to prevent the occurs, the float 4t settles into engagement with and seals the valve seat 41, thus preventing the pump from drawing air into the system.

I n automobile cooling systems, the pressure relief valve 22 may be constructed to open at any desired pressure,

By promoting the expulsion of all air from the cooling system, my invention provides several advantages. Upon When operation of the engine is terminated, the temperature of the engine tends to rise While that of the radiator tends If there were an air pocket in the radiator, its

During operation of the engine, the maintenance of the maximum pressure permitted by the valve 22 greatly lessens the likelihood of vaporization at such diflicultly cooled areas and promotes proper cooling of all parts of the engine.

I claim as my invention:

1. In combination with the cooling system of a jacketed internal combustion engine having a coolant-circulat ing pump for circulating liquid coolant through said system and a pressure-relief valve controlling communica- References Cited in the file of this patent UNITED STATES PATENTS Muir May 24, 1927 Illsley May 21, 1940 

